Caller: "It was really scary and frightening and it just happened few seconds ago."

A caller told the dispatcher a bald person wearing a red shirt was running from the scene.

Det. Jason Davila called the case an assassination.

“Mr. Santos was targeted," said Davila. "He fled from his vehicle and he was pursued by this individual until Mr. Santos fell to the ground.”

Davila said a 2001 Chrysler was seen driving in the area before the incident.

“We have a lot of physical evidence, we just don't have anything that's directly leading us to a suspect at this point," he said.

Santos worked at C3/Customer Contact Channels, a call center. They released a statement to News 4 Tucson.

"First and foremost our hearts go out to Jesus’ family. We have lost a member of our C3 family too. Our first responsibility is to assist the family in any way we can. And next is to our employees who knew him and are equally saddened by this tragedy. We have reached out to the family and have been in contact with them to provide support."

Some of his co-workers said he was the nicest person, always smiling, a good family man and a good friend. Davila said not one person they spoke too had anything negative to say about Santos.